drivers/net/netconsole.c

   1 /*
   2  *  linux/drivers/net/netconsole.c
   3  *
   4  *  Copyright (C) 2001  Ingo Molnar <mingo@redhat.com>
   5  *
   6  *  This file contains the implementation of an IRQ-safe, crash-safe
   7  *  kernel console implementation that outputs kernel messages to the
   8  *  network.
   9  *
  10  * Modification history:
  11  *
  12  * 2001-09-17    started by Ingo Molnar.
  13  * 2003-08-11    2.6 port by Matt Mackall
  14  *               simplified options
  15  *               generic card hooks
  16  *               works non-modular
  17  * 2003-09-07    rewritten with netpoll api
  18  */
  19
  20 /****************************************************************
  21  *      This program is free software; you can redistribute it and/or modify
  22  *      it under the terms of the GNU General Public License as published by
  23  *      the Free Software Foundation; either version 2, or (at your option)
  24  *      any later version.
  25  *
  26  *      This program is distributed in the hope that it will be useful,
  27  *      but WITHOUT ANY WARRANTY; without even the implied warranty of
  28  *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  29  *      GNU General Public License for more details.
  30  *
  31  *      You should have received a copy of the GNU General Public License
  32  *      along with this program; if not, write to the Free Software
  33  *      Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  34  *
  35  ****************************************************************/
  36
  37 #include <linux/mm.h>
  38 #include <linux/init.h>
  39 #include <linux/module.h>
  40 #include <linux/slab.h>
  41 #include <linux/console.h>
  42 #include <linux/moduleparam.h>
  43 #include <linux/string.h>
  44 #include <linux/netpoll.h>
  45 #include <linux/inet.h>
  46 #include <linux/configfs.h>
  47
  48 MODULE_AUTHOR("Maintainer: Matt Mackall <mpm@selenic.com>");
  49 MODULE_DESCRIPTION("Console driver for network interfaces");
  50 MODULE_LICENSE("GPL");
  51
  52 #define MAX_PARAM_LENGTH        256
  53 #define MAX_PRINT_CHUNK         1000
  54
  55 static char config[MAX_PARAM_LENGTH];
  56 module_param_string(netconsole, config, MAX_PARAM_LENGTH, 0);
  57 MODULE_PARM_DESC(netconsole, " netconsole=[src-port]@[src-ip]/[dev],[tgt-port]@<tgt-ip>/[tgt-macaddr]");
  58
  59 #ifndef MODULE
  60 static int __init option_setup(char *opt)
  61 {
  62         strlcpy(config, opt, MAX_PARAM_LENGTH);
  63         return 1;
  64 }
  65 __setup("netconsole=", option_setup);
  66 #endif  /* MODULE */
  67
  68 /* Linked list of all configured targets */
  69 static LIST_HEAD(target_list);
  70
  71 /* This needs to be a spinlock because write_msg() cannot sleep */
  72 static DEFINE_SPINLOCK(target_list_lock);
  73
  74 /**
  75  * struct netconsole_target - Represents a configured netconsole target.
  76  * @list:       Links this target into the target_list.
  77  * @item:       Links us into the configfs subsystem hierarchy.
  78  * @enabled:    On / off knob to enable / disable target.
  79  *              Visible from userspace (read-write).
  80  *              We maintain a strict 1:1 correspondence between this and
  81  *              whether the corresponding netpoll is active or inactive.
  82  *              Also, other parameters of a target may be modified at
  83  *              runtime only when it is disabled (enabled == 0).
  84  * @np:         The netpoll structure for this target.
  85  *              Contains the other userspace visible parameters:
  86  *              dev_name        (read-write)
  87  *              local_port      (read-write)
  88  *              remote_port     (read-write)
  89  *              local_ip        (read-write)
  90  *              remote_ip       (read-write)
  91  *              local_mac       (read-only)
  92  *              remote_mac      (read-write)
  93  */
  94 struct netconsole_target {
  95         struct list_head        list;
  96 #ifdef  CONFIG_NETCONSOLE_DYNAMIC
  97         struct config_item      item;
  98 #endif
  99         int                     enabled;
 100         struct netpoll          np;
 101 };
 102
 103 #ifdef  CONFIG_NETCONSOLE_DYNAMIC
 104
 105 static struct configfs_subsystem netconsole_subsys;
 106
 107 static int __init dynamic_netconsole_init(void)
 108 {
 109         config_group_init(&netconsole_subsys.su_group);
 110         mutex_init(&netconsole_subsys.su_mutex);
 111         return configfs_register_subsystem(&netconsole_subsys);
 112 }
 113
 114 static void __exit dynamic_netconsole_exit(void)
 115 {
 116         configfs_unregister_subsystem(&netconsole_subsys);
 117 }
 118
 119 /*
 120  * Targets that were created by parsing the boot/module option string
 121  * do not exist in the configfs hierarchy (and have NULL names) and will
 122  * never go away, so make these a no-op for them.
 123  */
 124 static void netconsole_target_get(struct netconsole_target *nt)
 125 {
 126         if (config_item_name(&nt->item))
 127                 config_item_get(&nt->item);
 128 }
 129
 130 static void netconsole_target_put(struct netconsole_target *nt)
 131 {
 132         if (config_item_name(&nt->item))
 133                 config_item_put(&nt->item);
 134 }
 135
 136 #else   /* !CONFIG_NETCONSOLE_DYNAMIC */
 137
 138 static int __init dynamic_netconsole_init(void)
 139 {
 140         return 0;
 141 }
 142
 143 static void __exit dynamic_netconsole_exit(void)
 144 {
 145 }
 146
 147 /*
 148  * No danger of targets going away from under us when dynamic
 149  * reconfigurability is off.
 150  */
 151 static void netconsole_target_get(struct netconsole_target *nt)
 152 {
 153 }
 154
 155 static void netconsole_target_put(struct netconsole_target *nt)
 156 {
 157 }
 158
 159 #endif  /* CONFIG_NETCONSOLE_DYNAMIC */
 160
 161 /* Allocate new target (from boot/module param) and setup netpoll for it */
 162 static struct netconsole_target *alloc_param_target(char *target_config)
 163 {
 164         int err = -ENOMEM;
 165         struct netconsole_target *nt;
 166
 167         /*
 168          * Allocate and initialize with defaults.
 169          * Note that these targets get their config_item fields zeroed-out.
 170          */
 171         nt = kzalloc(sizeof(*nt), GFP_KERNEL);
 172         if (!nt) {
 173                 printk(KERN_ERR "netconsole: failed to allocate memory\n");
 174                 goto fail;
 175         }
 176
 177         nt->np.name = "netconsole";
 178         strlcpy(nt->np.dev_name, "eth0", IFNAMSIZ);
 179         nt->np.local_port = 6665;
 180         nt->np.remote_port = 6666;
 181         memset(nt->np.remote_mac, 0xff, ETH_ALEN);
 182
 183         /* Parse parameters and setup netpoll */
 184         err = netpoll_parse_options(&nt->np, target_config);
 185         if (err)
 186                 goto fail;
 187
 188         err = netpoll_setup(&nt->np);
 189         if (err)
 190                 goto fail;
 191
 192         nt->enabled = 1;
 193
 194         return nt;
 195
 196 fail:
 197         kfree(nt);
 198         return ERR_PTR(err);
 199 }
 200
 201 /* Cleanup netpoll for given target (from boot/module param) and free it */
 202 static void free_param_target(struct netconsole_target *nt)
 203 {
 204         netpoll_cleanup(&nt->np);
 205         kfree(nt);
 206 }
 207
 208 #ifdef  CONFIG_NETCONSOLE_DYNAMIC
 209
 210 /*
 211  * Our subsystem hierarchy is:
 212  *
 213  * /sys/kernel/config/netconsole/
 214  *                              |
 215  *                              <target>/
 216  *                              |       enabled
 217  *                              |       dev_name
 218  *                              |       local_port
 219  *                              |       remote_port
 220  *                              |       local_ip
 221  *                              |       remote_ip
 222  *                              |       local_mac
 223  *                              |       remote_mac
 224  *                              |
 225  *                              <target>/...
 226  */
 227
 228 struct netconsole_target_attr {
 229         struct configfs_attribute       attr;
 230         ssize_t                         (*show)(struct netconsole_target *nt,
 231                                                 char *buf);
 232         ssize_t                         (*store)(struct netconsole_target *nt,
 233                                                  const char *buf,
 234                                                  size_t count);
 235 };
 236
 237 static struct netconsole_target *to_target(struct config_item *item)
 238 {
 239         return item ?
 240                 container_of(item, struct netconsole_target, item) :
 241                 NULL;
 242 }
 243
 244 /*
 245  * Attribute operations for netconsole_target.
 246  */
 247
 248 static ssize_t show_enabled(struct netconsole_target *nt, char *buf)
 249 {
 250         return snprintf(buf, PAGE_SIZE, "%d\n", nt->enabled);
 251 }
 252
 253 static ssize_t show_dev_name(struct netconsole_target *nt, char *buf)
 254 {
 255         return snprintf(buf, PAGE_SIZE, "%s\n", nt->np.dev_name);
 256 }
 257
 258 static ssize_t show_local_port(struct netconsole_target *nt, char *buf)
 259 {
 260         return snprintf(buf, PAGE_SIZE, "%d\n", nt->np.local_port);
 261 }
 262
 263 static ssize_t show_remote_port(struct netconsole_target *nt, char *buf)
 264 {
 265         return snprintf(buf, PAGE_SIZE, "%d\n", nt->np.remote_port);
 266 }
 267
 268 static ssize_t show_local_ip(struct netconsole_target *nt, char *buf)
 269 {
 270         return snprintf(buf, PAGE_SIZE, "%pI4\n", &nt->np.local_ip);
 271 }
 272
 273 static ssize_t show_remote_ip(struct netconsole_target *nt, char *buf)
 274 {
 275         return snprintf(buf, PAGE_SIZE, "%pI4\n", &nt->np.remote_ip);
 276 }
 277
 278 static ssize_t show_local_mac(struct netconsole_target *nt, char *buf)
 279 {
 280         struct net_device *dev = nt->np.dev;
 281         static const u8 bcast[ETH_ALEN] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
 282
 283         return snprintf(buf, PAGE_SIZE, "%pM\n", dev ? dev->dev_addr : bcast);
 284 }
 285
 286 static ssize_t show_remote_mac(struct netconsole_target *nt, char *buf)
 287 {
 288         return snprintf(buf, PAGE_SIZE, "%pM\n", nt->np.remote_mac);
 289 }
 290
 291 /*
 292  * This one is special -- targets created through the configfs interface
 293  * are not enabled (and the corresponding netpoll activated) by default.
 294  * The user is expected to set the desired parameters first (which
 295  * would enable him to dynamically add new netpoll targets for new
 296  * network interfaces as and when they come up).
 297  */
 298 static ssize_t store_enabled(struct netconsole_target *nt,
 299                              const char *buf,
 300                              size_t count)
 301 {
 302         int enabled;
 303         int err;
 304
 305         err = kstrtoint(buf, 10, &enabled);
 306         if (err < 0)
 307                 return err;
 308         if (enabled < 0 || enabled > 1)
 309                 return -EINVAL;
 310         if (enabled == nt->enabled) {
 311                 printk(KERN_INFO "netconsole: network logging has already %s\n",
 312                                 nt->enabled ? "started" : "stopped");
 313                 return -EINVAL;
 314         }
 315
 316         if (enabled) {  /* 1 */
 317
 318                 /*
 319                  * Skip netpoll_parse_options() -- all the attributes are
 320                  * already configured via configfs. Just print them out.
 321                  */
 322                 netpoll_print_options(&nt->np);
 323
 324                 err = netpoll_setup(&nt->np);
 325                 if (err)
 326                         return err;
 327
 328                 printk(KERN_INFO "netconsole: network logging started\n");
 329
 330         } else {        /* 0 */
 331                 netpoll_cleanup(&nt->np);
 332         }
 333
 334         nt->enabled = enabled;
 335
 336         return strnlen(buf, count);
 337 }
 338
 339 static ssize_t store_dev_name(struct netconsole_target *nt,
 340                               const char *buf,
 341                               size_t count)
 342 {
 343         size_t len;
 344
 345         if (nt->enabled) {
 346                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 347                                 "disable to update parameters\n",
 348                                 config_item_name(&nt->item));
 349                 return -EINVAL;
 350         }
 351
 352         strlcpy(nt->np.dev_name, buf, IFNAMSIZ);
 353
 354         /* Get rid of possible trailing newline from echo(1) */
 355         len = strnlen(nt->np.dev_name, IFNAMSIZ);
 356         if (nt->np.dev_name[len - 1] == '\n')
 357                 nt->np.dev_name[len - 1] = '\0';
 358
 359         return strnlen(buf, count);
 360 }
 361
 362 static ssize_t store_local_port(struct netconsole_target *nt,
 363                                 const char *buf,
 364                                 size_t count)
 365 {
 366         int rv;
 367
 368         if (nt->enabled) {
 369                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 370                                 "disable to update parameters\n",
 371                                 config_item_name(&nt->item));
 372                 return -EINVAL;
 373         }
 374
 375         rv = kstrtou16(buf, 10, &nt->np.local_port);
 376         if (rv < 0)
 377                 return rv;
 378         return strnlen(buf, count);
 379 }
 380
 381 static ssize_t store_remote_port(struct netconsole_target *nt,
 382                                  const char *buf,
 383                                  size_t count)
 384 {
 385         int rv;
 386
 387         if (nt->enabled) {
 388                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 389                                 "disable to update parameters\n",
 390                                 config_item_name(&nt->item));
 391                 return -EINVAL;
 392         }
 393
 394         rv = kstrtou16(buf, 10, &nt->np.remote_port);
 395         if (rv < 0)
 396                 return rv;
 397         return strnlen(buf, count);
 398 }
 399
 400 static ssize_t store_local_ip(struct netconsole_target *nt,
 401                               const char *buf,
 402                               size_t count)
 403 {
 404         if (nt->enabled) {
 405                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 406                                 "disable to update parameters\n",
 407                                 config_item_name(&nt->item));
 408                 return -EINVAL;
 409         }
 410
 411         nt->np.local_ip = in_aton(buf);
 412
 413         return strnlen(buf, count);
 414 }
 415
 416 static ssize_t store_remote_ip(struct netconsole_target *nt,
 417                                const char *buf,
 418                                size_t count)
 419 {
 420         if (nt->enabled) {
 421                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 422                                 "disable to update parameters\n",
 423                                 config_item_name(&nt->item));
 424                 return -EINVAL;
 425         }
 426
 427         nt->np.remote_ip = in_aton(buf);
 428
 429         return strnlen(buf, count);
 430 }
 431
 432 static ssize_t store_remote_mac(struct netconsole_target *nt,
 433                                 const char *buf,
 434                                 size_t count)
 435 {
 436         u8 remote_mac[ETH_ALEN];
 437
 438         if (nt->enabled) {
 439                 printk(KERN_ERR "netconsole: target (%s) is enabled, "
 440                                 "disable to update parameters\n",
 441                                 config_item_name(&nt->item));
 442                 return -EINVAL;
 443         }
 444
 445         if (!mac_pton(buf, remote_mac))
 446                 return -EINVAL;
 447         if (buf[3 * ETH_ALEN - 1] && buf[3 * ETH_ALEN - 1] != '\n')
 448                 return -EINVAL;
 449         memcpy(nt->np.remote_mac, remote_mac, ETH_ALEN);
 450
 451         return strnlen(buf, count);
 452 }
 453
 454 /*
 455  * Attribute definitions for netconsole_target.
 456  */
 457
 458 #define NETCONSOLE_TARGET_ATTR_RO(_name)                                \
 459 static struct netconsole_target_attr netconsole_target_##_name =        \
 460         __CONFIGFS_ATTR(_name, S_IRUGO, show_##_name, NULL)
 461
 462 #define NETCONSOLE_TARGET_ATTR_RW(_name)                                \
 463 static struct netconsole_target_attr netconsole_target_##_name =        \
 464         __CONFIGFS_ATTR(_name, S_IRUGO | S_IWUSR, show_##_name, store_##_name)
 465
 466 NETCONSOLE_TARGET_ATTR_RW(enabled);
 467 NETCONSOLE_TARGET_ATTR_RW(dev_name);
 468 NETCONSOLE_TARGET_ATTR_RW(local_port);
 469 NETCONSOLE_TARGET_ATTR_RW(remote_port);
 470 NETCONSOLE_TARGET_ATTR_RW(local_ip);
 471 NETCONSOLE_TARGET_ATTR_RW(remote_ip);
 472 NETCONSOLE_TARGET_ATTR_RO(local_mac);
 473 NETCONSOLE_TARGET_ATTR_RW(remote_mac);
 474
 475 static struct configfs_attribute *netconsole_target_attrs[] = {
 476         &netconsole_target_enabled.attr,
 477         &netconsole_target_dev_name.attr,
 478         &netconsole_target_local_port.attr,
 479         &netconsole_target_remote_port.attr,
 480         &netconsole_target_local_ip.attr,
 481         &netconsole_target_remote_ip.attr,
 482         &netconsole_target_local_mac.attr,
 483         &netconsole_target_remote_mac.attr,
 484         NULL,
 485 };
 486
 487 /*
 488  * Item operations and type for netconsole_target.
 489  */
 490
 491 static void netconsole_target_release(struct config_item *item)
 492 {
 493         kfree(to_target(item));
 494 }
 495
 496 static ssize_t netconsole_target_attr_show(struct config_item *item,
 497                                            struct configfs_attribute *attr,
 498                                            char *buf)
 499 {
 500         ssize_t ret = -EINVAL;
 501         struct netconsole_target *nt = to_target(item);
 502         struct netconsole_target_attr *na =
 503                 container_of(attr, struct netconsole_target_attr, attr);
 504
 505         if (na->show)
 506                 ret = na->show(nt, buf);
 507
 508         return ret;
 509 }
 510
 511 static ssize_t netconsole_target_attr_store(struct config_item *item,
 512                                             struct configfs_attribute *attr,
 513                                             const char *buf,
 514                                             size_t count)
 515 {
 516         ssize_t ret = -EINVAL;
 517         struct netconsole_target *nt = to_target(item);
 518         struct netconsole_target_attr *na =
 519                 container_of(attr, struct netconsole_target_attr, attr);
 520
 521         if (na->store)
 522                 ret = na->store(nt, buf, count);
 523
 524         return ret;
 525 }
 526
 527 static struct configfs_item_operations netconsole_target_item_ops = {
 528         .release                = netconsole_target_release,
 529         .show_attribute         = netconsole_target_attr_show,
 530         .store_attribute        = netconsole_target_attr_store,
 531 };
 532
 533 static struct config_item_type netconsole_target_type = {
 534         .ct_attrs               = netconsole_target_attrs,
 535         .ct_item_ops            = &netconsole_target_item_ops,
 536         .ct_owner               = THIS_MODULE,
 537 };
 538
 539 /*
 540  * Group operations and type for netconsole_subsys.
 541  */
 542
 543 static struct config_item *make_netconsole_target(struct config_group *group,
 544                                                   const char *name)
 545 {
 546         unsigned long flags;
 547         struct netconsole_target *nt;
 548
 549         /*
 550          * Allocate and initialize with defaults.
 551          * Target is disabled at creation (enabled == 0).
 552          */
 553         nt = kzalloc(sizeof(*nt), GFP_KERNEL);
 554         if (!nt) {
 555                 printk(KERN_ERR "netconsole: failed to allocate memory\n");
 556                 return ERR_PTR(-ENOMEM);
 557         }
 558
 559         nt->np.name = "netconsole";
 560         strlcpy(nt->np.dev_name, "eth0", IFNAMSIZ);
 561         nt->np.local_port = 6665;
 562         nt->np.remote_port = 6666;
 563         memset(nt->np.remote_mac, 0xff, ETH_ALEN);
 564
 565         /* Initialize the config_item member */
 566         config_item_init_type_name(&nt->item, name, &netconsole_target_type);
 567
 568         /* Adding, but it is disabled */
 569         spin_lock_irqsave(&target_list_lock, flags);
 570         list_add(&nt->list, &target_list);
 571         spin_unlock_irqrestore(&target_list_lock, flags);
 572
 573         return &nt->item;
 574 }
 575
 576 static void drop_netconsole_target(struct config_group *group,
 577                                    struct config_item *item)
 578 {
 579         unsigned long flags;
 580         struct netconsole_target *nt = to_target(item);
 581
 582         spin_lock_irqsave(&target_list_lock, flags);
 583         list_del(&nt->list);
 584         spin_unlock_irqrestore(&target_list_lock, flags);
 585
 586         /*
 587          * The target may have never been enabled, or was manually disabled
 588          * before being removed so netpoll may have already been cleaned up.
 589          */
 590         if (nt->enabled)
 591                 netpoll_cleanup(&nt->np);
 592
 593         config_item_put(&nt->item);
 594 }
 595
 596 static struct configfs_group_operations netconsole_subsys_group_ops = {
 597         .make_item      = make_netconsole_target,
 598         .drop_item      = drop_netconsole_target,
 599 };
 600
 601 static struct config_item_type netconsole_subsys_type = {
 602         .ct_group_ops   = &netconsole_subsys_group_ops,
 603         .ct_owner       = THIS_MODULE,
 604 };
 605
 606 /* The netconsole configfs subsystem */
 607 static struct configfs_subsystem netconsole_subsys = {
 608         .su_group       = {
 609                 .cg_item        = {
 610                         .ci_namebuf     = "netconsole",
 611                         .ci_type        = &netconsole_subsys_type,
 612                 },
 613         },
 614 };
 615
 616 #endif  /* CONFIG_NETCONSOLE_DYNAMIC */
 617
 618 /* Handle network interface device notifications */
 619 static int netconsole_netdev_event(struct notifier_block *this,
 620                                    unsigned long event,
 621                                    void *ptr)
 622 {
 623         unsigned long flags;
 624         struct netconsole_target *nt;
 625         struct net_device *dev = ptr;
 626         bool stopped = false;
 627
 628         if (!(event == NETDEV_CHANGENAME || event == NETDEV_UNREGISTER ||
 629               event == NETDEV_RELEASE || event == NETDEV_JOIN))
 630                 goto done;
 631
 632         spin_lock_irqsave(&target_list_lock, flags);
 633         list_for_each_entry(nt, &target_list, list) {
 634                 netconsole_target_get(nt);
 635                 if (nt->np.dev == dev) {
 636                         switch (event) {
 637                         case NETDEV_CHANGENAME:
 638                                 strlcpy(nt->np.dev_name, dev->name, IFNAMSIZ);
 639                                 break;
 640                         case NETDEV_RELEASE:
 641                         case NETDEV_JOIN:
 642                         case NETDEV_UNREGISTER:
 643                                 /*
 644                                  * rtnl_lock already held
 645                                  */
 646                                 if (nt->np.dev) {
 647                                         spin_unlock_irqrestore(
 648                                                               &target_list_lock,
 649                                                               flags);
 650                                         __netpoll_cleanup(&nt->np);
 651                                         spin_lock_irqsave(&target_list_lock,
 652                                                           flags);
 653                                         dev_put(nt->np.dev);
 654                                         nt->np.dev = NULL;
 655                                         netconsole_target_put(nt);
 656                                 }
 657                                 nt->enabled = 0;
 658                                 stopped = true;
 659                                 break;
 660                         }
 661                 }
 662                 netconsole_target_put(nt);
 663         }
 664         spin_unlock_irqrestore(&target_list_lock, flags);
 665         if (stopped) {
 666                 printk(KERN_INFO "netconsole: network logging stopped on "
 667                        "interface %s as it ", dev->name);
 668                 switch (event) {
 669                 case NETDEV_UNREGISTER:
 670                         printk(KERN_CONT "unregistered\n");
 671                         break;
 672                 case NETDEV_RELEASE:
 673                         printk(KERN_CONT "released slaves\n");
 674                         break;
 675                 case NETDEV_JOIN:
 676                         printk(KERN_CONT "is joining a master device\n");
 677                         break;
 678                 }
 679         }
 680
 681 done:
 682         return NOTIFY_DONE;
 683 }
 684
 685 static struct notifier_block netconsole_netdev_notifier = {
 686         .notifier_call  = netconsole_netdev_event,
 687 };
 688
 689 static void write_msg(struct console *con, const char *msg, unsigned int len)
 690 {
 691         int frag, left;
 692         unsigned long flags;
 693         struct netconsole_target *nt;
 694         const char *tmp;
 695
 696         /* Avoid taking lock and disabling interrupts unnecessarily */
 697         if (list_empty(&target_list))
 698                 return;
 699
 700         spin_lock_irqsave(&target_list_lock, flags);
 701         list_for_each_entry(nt, &target_list, list) {
 702                 netconsole_target_get(nt);
 703                 if (nt->enabled && netif_running(nt->np.dev)) {
 704                         /*
 705                          * We nest this inside the for-each-target loop above
 706                          * so that we're able to get as much logging out to
 707                          * at least one target if we die inside here, instead
 708                          * of unnecessarily keeping all targets in lock-step.
 709                          */
 710                         tmp = msg;
 711                         for (left = len; left;) {
 712                                 frag = min(left, MAX_PRINT_CHUNK);
 713                                 netpoll_send_udp(&nt->np, tmp, frag);
 714                                 tmp += frag;
 715                                 left -= frag;
 716                         }
 717                 }
 718                 netconsole_target_put(nt);
 719         }
 720         spin_unlock_irqrestore(&target_list_lock, flags);
 721 }
 722
 723 static struct console netconsole = {
 724         .name   = "netcon",
 725         .flags  = CON_ENABLED,
 726         .write  = write_msg,
 727 };
 728
 729 static int __init init_netconsole(void)
 730 {
 731         int err;
 732         struct netconsole_target *nt, *tmp;
 733         unsigned long flags;
 734         char *target_config;
 735         char *input = config;
 736
 737         if (strnlen(input, MAX_PARAM_LENGTH)) {
 738                 while ((target_config = strsep(&input, ";"))) {
 739                         nt = alloc_param_target(target_config);
 740                         if (IS_ERR(nt)) {
 741                                 err = PTR_ERR(nt);
 742                                 goto fail;
 743                         }
 744                         /* Dump existing printks when we register */
 745                         netconsole.flags |= CON_PRINTBUFFER;
 746
 747                         spin_lock_irqsave(&target_list_lock, flags);
 748                         list_add(&nt->list, &target_list);
 749                         spin_unlock_irqrestore(&target_list_lock, flags);
 750                 }
 751         }
 752
 753         err = register_netdevice_notifier(&netconsole_netdev_notifier);
 754         if (err)
 755                 goto fail;
 756
 757         err = dynamic_netconsole_init();
 758         if (err)
 759                 goto undonotifier;
 760
 761         register_console(&netconsole);
 762         printk(KERN_INFO "netconsole: network logging started\n");
 763
 764         return err;
 765
 766 undonotifier:
 767         unregister_netdevice_notifier(&netconsole_netdev_notifier);
 768
 769 fail:
 770         printk(KERN_ERR "netconsole: cleaning up\n");
 771
 772         /*
 773          * Remove all targets and destroy them (only targets created
 774          * from the boot/module option exist here). Skipping the list
 775          * lock is safe here, and netpoll_cleanup() will sleep.
 776          */
 777         list_for_each_entry_safe(nt, tmp, &target_list, list) {
 778                 list_del(&nt->list);
 779                 free_param_target(nt);
 780         }
 781
 782         return err;
 783 }
 784
 785 static void __exit cleanup_netconsole(void)
 786 {
 787         struct netconsole_target *nt, *tmp;
 788
 789         unregister_console(&netconsole);
 790         dynamic_netconsole_exit();
 791         unregister_netdevice_notifier(&netconsole_netdev_notifier);
 792
 793         /*
 794          * Targets created via configfs pin references on our module
 795          * and would first be rmdir(2)'ed from userspace. We reach
 796          * here only when they are already destroyed, and only those
 797          * created from the boot/module option are left, so remove and
 798          * destroy them. Skipping the list lock is safe here, and
 799          * netpoll_cleanup() will sleep.
 800          */
 801         list_for_each_entry_safe(nt, tmp, &target_list, list) {
 802                 list_del(&nt->list);
 803                 free_param_target(nt);
 804         }
 805 }
 806
 807 /*
 808  * Use late_initcall to ensure netconsole is
 809  * initialized after network device driver if built-in.
 810  *
 811  * late_initcall() and module_init() are identical if built as module.
 812  */
 813 late_initcall(init_netconsole);
 814 module_exit(cleanup_netconsole);